Pressure detection device and pressure detection method

ABSTRACT

The pressure detection device includes a buffer member deformable by a pressure change, including one or more magnets, and a sensor assembly including one or more magnetic sensors to detect a variation of a magnetic field accompanied by deformation of the buffer member.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the priority based on Japanese PatentApplications No. 2008-48557 filed on Feb. 28, 2008, and No. 2009-11653filed on Jan. 22, 2009, the disclosures of which are hereby incorporatedby reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pressure detection technique.

2. Description of the Related Art

Some conventional pressure detection devices detect a pressing forcebased on variation of a resistance value of a pressure sensitive elementin response to the pressing force (see, for example, JP07-253374A).

There are, however, restrictions on the shape of the pressure sensitiveelement, and it is sometimes difficult to make the pressure sensitiveelement to have a desired shape.

SUMMARY

An object of the present invention is to provide a pressure detectiontechnology that is significantly different from the prior art technique.

According to an aspect of the present invention, a pressure detectiondevice is provided. The pressure detection device comprises: a buffermember deformable by a pressure change, including one or more magnets;and a sensor assembly including one or more magnetic sensors to detect avariation of a magnetic field accompanied by deformation of the buffermember.

According to this configuration, the buffer member is deformable to varythe magnetic field in response to a pressure change applied to thebuffer member. The magnetic sensor is used to detect such a variation ofthe magnetic field. The pressure detection device of this arrangementthus allows detection of a pressure change.

The present invention is not restricted to the pressure detection devicehaving any of the various arrangements discussed above but may beactualized by diversity of other applications, for example, a pressuredetection method, various apparatuses equipped with the pressuredetection device, such as moving bodies, robots, and steeringapparatuses, a control system utilizing the pressure detection device,and a recording medium in which the control system is recorded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematically illustrates the structure of a pressuredetection device in a first embodiment of the invention;

FIG. 2 is a block diagram showing the configuration of a control systemutilizing the pressure detection device of the first embodiment;

FIG. 3 is a block diagram showing the internal structure of the magneticsensor circuit 331;

FIGS. 4A and 4B show an example of the desired input-output relation ofthe pressure detection device;

FIGS. 5A and 5B show another example of the desired input-outputrelation of the pressure detection device;

FIG. 6 is a block diagram showing the configuration of another controlsystem utilizing the pressure detection device of the first embodiment;

FIGS. 7A and 7B schematically illustrate the structure of a pressuredetection device in a second embodiment of the invention;

FIGS. 8A-8C show a manufacturing process of the pressure detectiondevice of the second embodiment;

FIGS. 9A and 9B schematically illustrate the structure of a pressuredetection device in a third embodiment of the invention;

FIG. 10 schematically illustrates the structure of a pressure detectiondevice in a fourth embodiment of the invention;

FIG. 11 schematically shows the configuration of a vehicle equipped witha pressure detection device in a fifth embodiment of the invention;

FIG. 12 is a block diagram showing a control system of the vehicleequipped with the pressure detection device in the fifth embodiment;

FIG. 13 is a flowchart showing a control process of the drive assembly640 by the control circuit;

FIG. 14 schematically shows the structure of a vehicle equipped with apressure detection device in a sixth embodiment of the invention;

FIG. 15 schematically illustrates the configuration of a robot equippedwith a pressure detection device in a seventh embodiment of theinvention;

FIG. 16 schematically illustrates the structure of a steering apparatusequipped with a pressure detection device in an eighth embodiment of theinvention;

FIG. 17 schematically illustrates the structure of a pressure detectiondevice in a ninth embodiment of the invention;

FIG. 18 is a block diagram showing the internal structure of themagnetic sensor circuit;

FIG. 19 shows the schematic structure of the sensor assembly;

FIG. 20 shows control of the magnetic sensor element group by theelement group controller;

FIG. 21 is a table showing one example of the sensor output SSA at acertain time; and

FIG. 22 visualizes the table of FIG. 21.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Next, aspects of the present invention will be described in thefollowing order on the basis of embodiments:

A. First Embodiment:

B. Second Embodiment

C. Third Embodiment

D. Fourth Embodiment

E. Fifth Embodiment

F. Sixth Embodiment

G. Seventh Embodiment

H. Eighth Embodiment

I. Ninth Embodiment

J. Modifications:

A. FIRST EMBODIMENT

FIG. 1 schematically illustrates the structure of a pressure detectiondevice 300 in a first embodiment of the invention. The pressuredetection device 300 includes a buffer member 340 with a permanentmagnet 320 embedded therein, and a sensor assembly 330 provided belowthe permanent magnet 320. The buffer member 340 is arranged to surroundthe sensor assembly 330. The permanent magnet 320 is magnetized in avertical direction in FIG. 1. The sensor assembly 330 has a magneticsensor circuit 331, a circuit board 332, and a magnetic yoke 333. Themagnetic sensor circuit 331 is fixed on the circuit board 332, and themagnetic yoke 333 is disposed on a rear face of the circuit board 332.The magnetic yoke 333 may be omitted when not required. The buffermember 340 is preferably made of a buffer material deformable to absorban external shock or vibration, such as sponge or polyurethane foam. Inthe pressure detection device 300 of this structure, in response todeformation of the buffer member 340 by an external pressing force PP,the magnetic field varies at the location of the magnetic sensor circuit331. The strength of the external pressing force PP is then detectableaccording to this variation of the magnetic field.

FIG. 2 is a block diagram showing the configuration of a control systemutilizing the pressure detection device 300 of the first embodiment. Thecontrol system of FIG. 2 includes the pressure detection device 300, acontrol circuit 500, and a controlled device 540. The control circuit500 has a power supply circuit 510, a CPU 520, and a communication unit530. The pressure detection device 300 has a connector 310, in additionto the magnetic sensor circuit 331 and the permanent magnet 320discussed above with reference to FIG. 1. The connector 310 works as aconnection terminal for electrically connecting the pressure detectiondevice 300 to the control circuit 500. The control circuit 500communicates with the pressure detection device 300, for example, bytransmission of digital signals.

The control circuit 500 controls the operations of the controlled device540, based on the detection result of the magnetic sensor circuit 331.The controlled device 540 may be any arbitrary device, for example, amotor or a heater. In a system having multiple magnetic sensor circuits331 connected to the control circuit 500, the control circuit 500identifies the respective multiple magnetic sensor circuits 331.

FIG. 3 is a block diagram showing the internal structure of the magneticsensor circuit 331. The magnetic sensor circuit 331 includes a magneticsensor element 410, an A-D converter 420, a characteristic converter430, a storage unit 440, a D-A converter 450, an amplifier 460, an IDcode recorder 470 functioning as the ID code storage unit, and acommunication unit 480. The magnetic sensor element 410 is constructed,for example, by a Hall element.

The communication unit 480 of the magnetic sensor circuit 331communicates with the communication unit 530 of the control circuit 500and receives a sensor ID and correction data for a sensor output SSA0from the control circuit 500. A sensor-specific ID uniquely allocated tothe magnetic sensor circuit 331 is recorded in the ID code recorder 470.Alternatively, the ID may be set in the ID code recorder 470 by anexternal switch 472. In the structure of FIG. 3, the external switch472, such as a dip switch, is used to set the ID in the ID code recorder470. The ID may be recorded or set in the magnetic sensor circuit 331 byany other arbitrary means. One modified structure adopts a nonvolatilememory for the ID code recorder 470 with omission of the external switch472. Upon matching of the ID supplied from the control circuit 500 withthe ID recorded or set in the ID code recorder 470, the communicationunit 480 stores the correction data supplied from the control circuit500 into the storage unit 440. In the system having the multiplemagnetic sensor circuits 331 connected to the control circuit 500, thecorrection data is transmittable to one specific magnetic sensor circuit331 selected among the multiple magnetic sensor circuits 331 by takingadvantage of such ID matching. The ID code recorder 470 and the externalswitch 472 may be omitted when not required. Any suitable structureother than the control circuit 500 may be adopted to send the correctiondata to the magnetic sensor circuit 331.

In the structure of FIG. 3, the correction data represents the contentsof a conversion table CT, which is stored in the storage unit 440. Thecharacteristic converter 430 utilizes this conversion table CT tocorrect the level of the sensor output SSA0 from the magnetic sensorelement 410. This correction aims to adjust the input-output relation ofthe pressure detection device 300 to a desired shape, that is, desiredinput and output characteristics. In the configuration of thisembodiment, the input of the pressure detection device 300 is themagnitude and the direction of the magnetic field varied by the externalpressing force PP. The output of the pressure detection device 300 is asensor output SSA of the magnetic sensor circuit 331. The sensor outputcorrected by the characteristic converter 430 is subject todigital-to-analog conversion in the D-A converter 450, is amplified bythe amplifier 460, and is output as the sensor output SSA.

Any of the following tables may be adopted for the conversion table CT:

(1) a first lookup table having the level of the non-corrected sensoroutput SSA0 as its input and the level of the corrected sensor outputSSA as its output;

(2) a second lookup table having the level of the non-corrected sensoroutput SSA0 as its input and the difference between the non-correctedsensor output SSA0 and the corrected sensor output SSA as its output;and

(3) a third lookup table having the level of the non-corrected sensoroutput SSA0 as its input and the ratio of the corrected sensor outputSSA to the non-corrected sensor output SSA0 as its output.

In application of the first lookup table, the characteristic converter430 refers to the first lookup table to directly obtain the correctedsensor output SSA. In application of the second lookup table, thecharacteristic converter 430 adds the difference read out from thesecond lookup table to the output of the magnetic sensor element 410 toobtain the corrected sensor output SSA. In application of the thirdlookup table, the characteristic converter 430 multiplies the output ofthe magnetic sensor element 410 by the ratio read out from the thirdlookup table to obtain the corrected sensor output SSA.

FIGS. 4A and 4B show an example of the desired input-output relation ofthe pressure detection device 300. FIG. 4A shows a non-converted(non-corrected) input-output relation, and FIG. 4B shows a converted(corrected) input-output relation. In these graphs of FIGS. 4A and 4B,the amount of pressure applied by the external pressing force PP isshown as abscissa and the sensor output SSA of the magnetic sensorcircuit 331 as ordinate. In this example, the non-linear input-outputrelation of FIG. 4A is converted and corrected to the linearinput-output relation of FIG. 4B. Such correction ensures a linearrelation between the input (the amount of pressure applied) and theoutput (the sensor output SSA), independently of the installationcondition of the pressure detection device 300. The control circuit 500then readily performs adequate controls by utilizing this correctedsensor output SSA.

FIGS. 5A and 5B show another example of the desired input-outputrelation of the pressure detection device 300. In this example, a linearinput-output relation of FIG. 5A is converted to a non-linearinput-output relation of FIG. 5B. The converted input-output relation(input-output characteristic) may be any of various shapes includinglinear shapes and non-linear shapes.

FIG. 6 is a block diagram showing the configuration of another controlsystem utilizing the pressure detection device 300 of the firstembodiment. The control system of FIG. 6 includes a heater 350 and atemperature sensor 360, in addition to the configuration of the controlsystem shown in FIG. 2. The temperature sensor 360 measures thetemperature of the permanent magnet 320 in a non-contact manner. Thetemperature sensor 360 may alternatively be a conventional contact-typesensor. The heater 350 works to keep the permanent magnet 320 at aconstant temperature and prevent a variation in hardness of the buffermaterial with a temperature variation. In a system having aninsufficient space for the heater, a lookup table or another suitablemeans may be applied to correct the result of pressure detection basedon the temperature detected by the temperature sensor and therebyeliminate the influence of a temperature variation on the hardness ofthe buffer material and the influence of the environmental temperatureon the magnetic field. The control circuit 500 controls the output ofthe heater 350 to keep the temperature of the permanent magnet 320 at adesired temperature level. The control system of this configurationenables the temperature of the permanent magnet 320 to be keptsubstantially constant irrespective of the environmental temperature andthus desirably stabilizes the magnetic field generated by the permanentmagnet 320. This arrangement ensures the precise detection of theexternal pressing force PP and the highly accurate control.

The pressure detection device of the first embodiment detects a pressurechange in response to a variation of the magnetic field caused bydeformation of the buffer member. Even in application of a thick buffermaterial for the buffer member, the pressure change is effectivelydetectable.

B. SECOND EMBODIMENT

FIG. 7 schematically illustrates the structure of a pressure detectiondevice 300 a in a second embodiment of the invention. The primarydifference from the pressure detection device 300 of the firstembodiment shown in FIG. 1 is that a buffer member 340 a includesmultiple permanent magnets 320 in an evenly dispersed arrangement.Otherwise the structure of the pressure detection device 300 a of thesecond embodiment is similar to the structure of the pressure detectiondevice 300 of the first embodiment. The multiple permanent magnets 320 aare preferably formed as tiny articles, such as powder articles, to beevenly dispersed in the buffer member 340 a.

FIG. 8 shows a manufacturing process of the pressure detection device300 a of the second embodiment. At a first step, the buffer member 340a, which is deformable by a pressure change, is provided as shown inFIG. 8A. The buffer member 340 includes tiny non-magnetized magnetmembers MM. At a second step, the tiny non-magnetized magnet members MMare magnetized in a vertical direction in FIG. 8 to generate thepermanent magnets 320 a as shown in FIG. 8B. At a third step, the sensorassembly 330 is provided in the lower portion of the buffer member 340 aas shown in FIG. 8C. This gives the pressure detection device 300 ahaving the buffer member 340 a with a large number of the tiny permanentmagnets 320 a in an evenly dispersed arrangement.

The pressure detection device of the second embodiment has the largenumber of tiny permanent magnets evenly dispersed in the buffer member.The pressure detection device of this structure detects a pressurechange in response to a variation of the magnetic field caused bydeformation of the buffer member, like the pressure detection device ofthe first embodiment. The multiple permanent magnets evenly dispersed inthe buffer member allow effective detection of a pressure change atvarious sites in the buffer member.

C. THIRD EMBODIMENT

FIGS. 9A and 9B schematically illustrate the structure of a pressuredetection device 300 b in a third embodiment of the invention. Theprimary difference from the pressure detection device 300 a of thesecond embodiment shown in FIGS. 7A and 7B is that a sensor assembly 330b includes multiple magnetic sensor circuits 331 a and 331 b arranged ina lateral direction in FIG. 9A. Otherwise the structure of the pressuredetection device 300 b of the third embodiment is similar to thestructure of the pressure detection device 300 a of the secondembodiment. The structure of FIG. 9A has the two magnetic sensorcircuits 331 a and 331 b, although the number of magnetic sensorcircuits is not restricted to two but may be a greater number. FIG. 9Bshows a distribution of pressure to the magnetic sensor circuit 331 aand the magnetic sensor circuit 331 b under application of an externalpressing force PP to the pressure detection device 300 b of the thirdembodiment. The position of application of the external pressing forcePP is off from the center of the buffer member 340 a to the side of themagnetic sensor circuit 331 a. A pressure value PP1 detected by themagnetic sensor circuit 331 a is accordingly greater than a pressurevalue PP2 detected by the magnetic sensor circuit 331 b. The magnitudeand the position of the external pressing force PP are detectable, basedon the outputs of the multiple magnetic sensor circuits 331 a and 331 b.

The pressure detection device of the third embodiment has the multiplemagnetic sensor circuits arranged in the lateral direction in the sensorassembly. The pressure detection device of this structure detects apressure change in response to a variation of the magnetic field causedby deformation of the buffer member, like the pressure detection devicesof the first and the second embodiments. In the structure of the thirdembodiment, the lateral arrangement of the multiple magnetic sensorcircuits allows detection of a spatial pressure distribution in thelateral direction. A two-dimensional arrangement of multiple magneticsensor circuits allows detection of a two-dimensional pressuredistribution. Another arrangement of multiple magnetic sensor circuitsalong a curved surface will allow detection of a pressure distributionalong the curved surface.

D. FOURTH EMBODIMENT

FIG. 10 schematically illustrates the structure of a pressure detectiondevice 300 c in a fourth embodiment of the invention. The primarydifference from the pressure detection device 300 b of the thirdembodiment shown in FIG. 9A is that a sensor assembly 330 c includesmultiple magnetic sensor circuits 331 a and 331 b arranged upward anddownward in a vertical direction in FIG. 10. Otherwise the structure ofthe pressure detection device 300 c of the fourth embodiment is similarto the structure of the pressure detection device 300 b of the thirdembodiment. The vertical arrangement of the multiple magnetic sensorcircuits 331 a and 331 b allows detection of external pressing forces PPand PL applied downward and upward onto the buffer member 340 a. Themagnetic yoke is omitted from the illustration of FIG. 10.

The pressure detection device of the fourth embodiment has the multiplemagnetic sensor circuits arranged in the vertical direction in thesensor assembly. The pressure detection device of this structure detectsa pressure change in response to a variation of the magnetic fieldcaused by deformation of the buffer member, like the pressure detectiondevices of the first through the third embodiments. In the structure ofthe fourth embodiment, the vertical arrangement of the multiple magneticsensor circuits allows detection of a spatial pressure distribution inthe vertical direction.

E. FIFTH EMBODIMENT

FIG. 11 schematically shows the configuration of a vehicle 600 equippedwith a pressure detection device in a fifth embodiment of the invention.The vehicle 600 includes a windshield 610, a pressure detector 620,wheels 630, and a compartment 650. The pressure detection device 300 bof the third embodiment shown in FIGS. 9A and 9B, for example, isapplied for the pressure detector 620. In the vehicle 600 of thisembodiment, the pressure detection device 300 b is arranged to coverpart of the body of the vehicle 600 with the buffer member 340 a (seeFIG. 9A). In one preferable application, a large number of magneticsensor circuits are substantially evenly arranged within the buffermember 340 a. The pressure detector 620 is, however, not restricted tothis pressure detection device 300 b but may be any of the otherpressure detection devices of the embodiments discussed above.

FIG. 12 is a block diagram showing a control system of the vehicle 600equipped with the pressure detection device 300 b in the fifthembodiment. The control system includes the pressure detection device300 b, a control circuit 500, a drive assembly 640, and wheels 630. Theinternal structure of the pressure detection device 300 b and thecontrol circuit 500 is substantially identical with the internalstructure of FIG. 2 and is thus not specifically described here. Thecontrol circuit 500 uses the information supplied from the pressuredetection device 300 b to control the operations of the drive assembly640. The drive assembly 640 preferably includes a drive control circuit(not shown) of controlling an actuator (for example, an electric motor)to drive the wheels 630.

FIG. 13 is a flowchart showing a control process of the drive assembly640 by the control circuit 500. At step S10, the communication unit 530of the control circuit 500 establishes communication with thecommunication unit 480 of the magnetic sensor circuit 331 to receive thesensor output SSA. At step S20, it is determined whether the receivedsensor output SSA reaches or exceeds a preset reference value. Upondetermination that the received sensor output SSA is not less than thepreset reference value, the control circuit 500 specifies the steeringcontrol and the braking amount according to the deformation indicated bythe sensor output SSA at step S30. For example, the control circuit 500steers the vehicle 600 in an opposite direction to the direction of thedetected pressure. In another example, the control circuit 500 stops thevehicle 600 in response to detection of a certain pressure. At step S40,the control circuit 500 controls the operations of the drive assembly640 according to the specification of step S30.

The vehicle equipped with any of the pressure detection devices of thefirst through the fourth embodiments detects a shock applied to thevehicle and performs the steering control and the braking control basedon the detection.

F. SIXTH EMBODIMENT

FIG. 14 schematically shows the structure of a vehicle 600 a equippedwith a pressure detection device in a sixth embodiment of the invention.The difference from the vehicle 600 of the fifth embodiment shown inFIG. 11 is only the location of the pressure detector 620 that coversonly part of a lower portion of the body of the vehicle 600 a. Otherwisethe configuration of the vehicle 600 a of the sixth embodiment issimilar to the configuration of the vehicle 600 of the fifth embodiment.It is generally preferable to locate the pressure detector 620 at aspecific portion that is expected to receive a shock applied to thevehicle.

The configuration of the sixth embodiment has the pressure detectiondevice located at only the specific portion especially requiringdetection of a shock, thus desirably reducing the manufacturing cost ofthe vehicle.

G. SEVENTH EMBODIMENT

FIG. 15 schematically illustrates the configuration of a robot 700equipped with a pressure detection device in a seventh embodiment of theinvention. The robot 700 includes a body 710, a visual sensing unit 720,a voice unit 730, a haptic unit 740, and a moving mechanism 750. Thepressure detection device 300 b of the third embodiment discussed aboveis applied for the haptic unit 740. The surface of the haptic unit 740is covered with the buffer member 340 a. For example, in response todetection of some pressing force applied to the haptic unit 740, acontrol circuit (not shown) may control a drive assembly (not shown) tooperate the robot 700. In response to detection of a specific pressureapplied to the haptic unit 740, the control circuit may assume that therobot 700 grips some object and control the operations of the robot 700.The visual sensing unit 720, the voice unit 730, and the movingmechanism 750 may be omitted when not required.

H. EIGHTH EMBODIMENT

FIG. 16 schematically illustrates the structure of a steering apparatus800 equipped with a pressure detection device in an eighth embodiment ofthe invention. The steering apparatus 800 includes a steering commandunit 810, a grip 820, and an operation panel 830. The steering apparatus800 may be attached to a vehicle (not shown). The pressure detectiondevice 300 b of the third embodiment discussed above is applied for thegrip 820. The surface of the grip 820 is covered with the buffer member340 a. For example, in response to no detection of the driver's grippingpressure applied to the grip 820 because of the driver's drowsy driving,a control circuit (not shown) may controls a drive assembly (not shown)of the vehicle to forcibly brake the vehicle. The operation panel 830may be omitted when not required.

I. NINTH EMBODIMENT

FIG. 17 schematically illustrates the structure of a pressure detectiondevice 300 d in a ninth embodiment of the invention. The primarydifference from the pressure detection device 300 a of the secondembodiment shown in FIGS. 7A and 7B is the structure of a sensorassembly 330 d. Otherwise the structure of the pressure detection device300 d of the ninth embodiment is similar to the structure of thepressure detection device 300 a of the second embodiment. In the sensorassembly 330 d of the ninth embodiment, a magnetic sensor circuit layer331 d and a circuit board layer 332 d are laid one upon the other andare spread over the whole lower face of the buffer member 340 a. Thecircuit board layer 332 d is made of a flexible material that is highlyflexible and is substantially deformable. The magnetic yoke is omittedfrom the illustration of FIG. 17.

FIG. 18 is a block diagram showing the internal structure of themagnetic sensor circuit 331 d. The primary difference from the magneticsensor circuit 331 of the second embodiment (see FIG. 3) is the presenceof a magnetic sensor element group 410 d instead of the single magneticsensor element 410, an element group controller 490, and an elementvalue table ET. The other structure and the operations of the magneticsensor circuit 331 d of the ninth embodiment are similar to those of themagnetic sensor circuit 331 of the second embodiment. The magneticsensor element group 410 d includes multiple magnetic sensor elements,for example, multiple Hall elements. The element group controller 490functions to control the magnetic sensor element group 410 d asdiscussed below. The element value table ET is provided in a storageunit 440 d to store sensor outputs from the magnetic sensor elementgroup 410 d. There may be multiple magnetic sensor circuits 331 d in thepressure detection device 300 d of the ninth embodiment. Upon matchingof an ID supplied from an external device (for example, the controlcircuit 500 shown in FIG. 2) with an ID recorded or set in the ID coderecorder 470 in one of the multiple magnetic sensor circuits 331 d, theexternal device is allowed to update the contents of the conversiontable CT stored in the magnetic sensor circuit 331 d with the matchingID. The external device (for example, the control circuit 500) is alsoallowed to read out data from the element value table ET via thecommunication unit 480.

FIG. 19 shows the schematic structure of the sensor assembly 330 d.Multiple magnetic sensor elements SD are evenly arranged on the flexiblecircuit board 332 d. The magnetic sensor elements SD are located atvertex positions of identical triangles, which are not actually butvirtually arranged in a tile-like arrangement. These multiple magneticsensor elements SD are collectively referred to as the ‘magnetic sensorelement group 410 d’. The triangles defining the locations of therespective magnetic sensor elements SD may be, for example, isoscelestriangles or equilateral triangles. The magnetic sensor elements SD areconnected to the element group controller 490 by means of independentlycommunicable buses. The constituents of the magnetic sensor circuit 331d other than the magnetic sensor element group 410 d and the elementgroup controller 490 are omitted from the illustration of FIG. 19.

FIG. 20 shows control of the magnetic sensor element group 410 d by theelement group controller 490. On the assumption of the magnetic sensorelements SD as a matrix, a certain magnetic sensor element SD isspecifiable as SD(i,j). For example, setting a switch NS1 ON (withswitches NS2 to NS4 set OFF) and subsequently setting a switch MS1 ON(with switches MS2 to MS5 OFF) gives a sensor output SSA0 from a certainmagnetic sensor element SD(1,1). In this manner, the element groupcontroller 490 successively obtains sensor outputs SSA0 from magneticsensor elements SD(1,1) to SD(4,5). The respective sensor outputs SSA0are transmitted together with identification information for identifyingthe respective magnetic sensor elements SD to the A-D converter 420 andare corrected according to the procedure discussed previously withreference to FIG. 3. The corrected sensor outputs SSA are stored in theelement value table ET.

FIG. 21 is a table showing one example of the sensor output SSA at acertain time. FIG. 22 visualizes the table of FIG. 21. As shown in FIGS.21 and 22, the magnitude of pressure application is detectable at eachpoint where the magnetic sensor element SD is located. A maximumpressure point among the respective points of the magnetic sensorelements SD is computable from the sensor outputs SSA.

The pressure detection device of the ninth embodiment detects a pressurechange in response to a variation of the magnetic field caused bydeformation of the buffer member, like the pressure detection devices ofthe first and the second embodiments. In the pressure detection deviceof the ninth embodiment, the magnetic sensor circuit layer is providedabove the flexible circuit board layer. This arrangement allowsdetection of a pressure change in objects of various shapes. The densearrangement of the evenly-distributed multiple magnetic sensor elementsgives a highly accurate pressure distribution as shown in FIG. 22.

J. MODIFICATIONS

The embodiments and their applications discussed above are to beconsidered in all aspects as illustrative and not restrictive. There maybe many modifications, changes, and alterations without departing fromthe scope or spirit of the main characteristics of the presentinvention. Some examples of possible modification are given below.

J1. MODIFIED EXAMPLE 1

In the pressure detection devices of the respective embodimentsdiscussed above, the magnet included in the buffer member is a permanentmagnet. This is, however, neither essential nor restrictive, and themagnet may be an electromagnet.

J2. MODIFIED EXAMPLE 2

In the pressure detection devices of the respective embodimentsdiscussed above, the permanent magnet is magnetized in the verticaldirection in the drawings. The magnetizing direction may be a lateraldirection or any suitable direction other than the vertical directionand the lateral direction.

J3. MODIFIED EXAMPLE 3

In the embodiments discussed above, the pressure detection devicecommunicates with the control circuit by transmission of digitalsignals. This is, however, neither essential nor restrictive. Thecommunication may be made by transmission of analog signals, by opticalcommunication, or via a power line.

J4. MODIFIED EXAMPLE 4

In the pressure detection devices of the respective embodimentsdiscussed above, the characteristic converter corrects the sensor outputSSA0 of the magnetic sensor element. A function operator using aspecified function may be used, instead of the characteristic converter,to perform the correction. The correction may be omitted when notrequired.

J5. MODIFIED EXAMPLE 5

The pressure detection device of the invention is applicable to variousapparatuses and equipment to detect a pressure. In the fifth and thesixth embodiments, the pressure detection device given as the pressuredetector is provided as part of the vehicle body. The location of thepressure detection device is, however, not restricted to the vehiclebody but may be determined according to the requirements. For example,the pressure detection device may be provided as part of a bumper, partof a door, or as part of a compartment interior. In the seventhembodiment, the pressure detection device given as the haptic unit isprovided on the arms of the robot. The location of the pressuredetection device is, however, not restricted to the arms of the robotbut may be the body of the robot or the legs of the robot. In the eighthembodiment, the pressure detection device is given as the grip of thesteering apparatus. The pressure detection device is, however, notrestricted to the grip of the steering apparatus but may be the steeringcommand unit or the operation panel of the steering apparatus.

J6. MODIFIED EXAMPLE 6

In the pressure detection device of the ninth embodiment, the magneticsensor elements SD are located at the vertex positions of the identicaltriangles in the tile-like arrangement. The magnetic sensor elements SDmay have any desired arrangement unless such modification does notdepart from the scope or spirit of the main characteristics of thepresent invention. For example, the magnetic sensor elements SD may beevenly arranged at vertex positions of identical squares or identicalhexagons in a tile-like arrangement. Any of such evenly-dispersedarrangements of multiple magnetic sensor elements gives a highlyaccurate pressure distribution detection.

1. A pressure detection device, comprising: a buffer member deformableby a pressure change, including one or more magnets; and a sensorassembly including one or more magnetic sensors to detect a variation ofa magnetic field accompanied by deformation of the buffer member.
 2. Thepressure detection device according to claim 1, wherein the buffermember includes a plurality of the magnets in an evenly dispersedarrangement.
 3. The pressure detection device according to claim 1,wherein the sensor assembly includes a plurality of the magneticsensors.
 4. A pressure detection device, comprising: a buffer memberdeformable by a pressure change, including a plurality of magnets; asensor assembly including a magnetic sensor to detect a variation of amagnetic field accompanied by deformation of the buffer member; whereinthe plurality of magnets are distributed in an evenly dispersedarrangement in the buffer member; and the magnetic sensor is provided ona flexible circuit board.
 5. The pressure detection device according toclaim 4, wherein the magnetic sensor includes a plurality of magneticsensor elements, and the plurality of magnetic sensor elements areevenly arranged on the flexible circuit board.
 6. The pressure detectiondevice according to claim 4, wherein the magnetic sensor includes aplurality of magnetic sensor elements, and the plurality of magneticsensor elements are located at vertex positions of identical virtualtriangles which are virtually arranged in a tile-like arrangement on theflexible circuit board.
 7. The pressure detection device according toclaim 4, wherein the magnetic sensor is provided in a plurality in thesensor assembly, each of the magnetic sensors includes: a communicationmodule that communicates with an external device; and an ID code storagemodule that stores an identification code allocated for identifying eachof the magnetic sensors, and the external device is accessible to anymagnetic sensor among the magnetic sensors by referring to theidentification code stored in the ID code storage module.
 8. A method ofdetecting pressure, comprising the steps of: (a) providing a buffermember deformable by a pressure change, including one or more magnets;and (b) detecting a variation of a magnetic field accompanied bydeformation of the buffer member, to thereby detect a pressure appliedto the buffer member.
 9. A moving body, comprising: the pressuredetection device according to claim 1; and a controller that controlsthe moving body, based on a detection result of the pressure detectiondevice.
 10. A robot, comprising: the pressure detection device accordingto claim 1; and a controller that controls the robot, based on adetection result of the pressure detection device.
 11. A steeringapparatus, comprising: the pressure detection device according to claim1; and a controller that controls a moving body equipped with thesteering apparatus, based on a detection result of the pressuredetection device.